1. Field of the Invention
The present invention relates to devices for observing the interior contents of a vessel or process pipeline, and more particularly to a module for introducing illuminating radiation into the vessel or pipeline in an efficient manner without substantially interfering with the opportunity to view the illuminated contents.
2. Description of the Related Art
It is known to use various devices for direct or remote viewing of the interior of a pressure vessel, reaction vessel, process pipeline, or the like. A simple device for this purpose is a transparent viewing window provided in a wall of the vessel or pipeline. By looking through this window, an operator can observe liquid levels, color changes, and other visually determinable factors taking place within the vessel or pipe. Several of these viewing windows are disclosed, for example, in U.S. Pat. Nos. 2,744,487; 3,299,851; 3,837,226; and 4,245,566. One problem associated with these viewing windows is that a lack of illumination hinders observation of the contents.
To overcome the problem of illumination, Thomas Canty invented a light pipeline device as described in U.S. Pat. No. 4,746,178 for illuminating the interior of a pressure vessel. The device comprises a housing containing a fiber optic rod running straight from an external light source to a fused glass, laminated barrier disc. The unit is securely mounted on the vessel apart from a separate viewing window, with the barrier disc being arranged adjacent the interior of the vessel, whereby source light is transmitted to illuminate the vessel contents. Although this advancement significantly helps with viewing, it requires another separate aperture through the vessel wall for illumination in addition to the aperture provided for viewing. Also, illuminating through the fused glass barrier disc creates unwanted reflections that hinder viewed image quality.
It is also known, as a matter of common practice, to simply position a light source near a viewing window such that both illumination and viewing take place through the same window in the vessel. This approach is less than ideal because the light source blocks a significant portion of the viewing window, leaving only a small portion of the window for viewing, and illumination light is reflected by the viewing window such that it interferes with viewing instead of illuminating the contents of the vessel as intended.
Combination illumination and camera viewing units are known in the prior art, for example from U.S. Pat. No. 5,230,556 to Canty et al. Units of this type include a centrally located camera for automatic viewing through a sight glass and a light guide delivering light through the sight glass adjacent the camera lens for illumination along an axis substantially parallel to the camera lens axis. This arrangement does not allow an on-site operator to look through the sight glass to view interior contents because the sight glass is blocked by the camera and light guide. Moreover, in the apparatus described in the ""556 patent, the light guide cannot be inserted beyond the sight glass into the vessel, and illumination energy per unit volume dissipates quickly with distance into the vessel. Consequently, the effectiveness of external illumination units of the prior art is particularly diminished in those situations where the sight glass is positioned on a nozzle entry which extends out from the interior wall surface of the vessel by several inches.
Another problem associated with viewing windows of the prior art is that an internal surface of the viewing window can become clouded or blocked by process constituents coming into contact therewith. This problem is exacerbated where heat from an illumination source causes the internal contents to bake onto the viewing window.
It is therefore an object of the present invention to enable introduction of cool illumination into the process and allow for maximum transmission of illuminating radiation into the interior of the vessel for viewing purposes.
It is another object of the present invention to provide a modular means of cool illumination that can be mounted in combination with a sealed transparent or translucent sight glass without blocking a substantial portion of the sight glass.
It is a further object of the present invention to provide a modular means of cool illumination that can be mounted in combination with a sealed camera unit or other radiation detector unit without blocking a substantial portion of the field of view of the camera.
It is a further object of the present invention to provide a modular illumination device that can be combined with either a sight glass or an automatic viewing unit as desired.
It is a further object of the present invention to provide an insertable means of illumination that will eliminate reflection into the operator""s eyes or camera lens, thereby maximizing viewing capacity and accuracy.
It is a further object of the present invention to provide an insertable means of illumination that can be installed at a nozzle port to effectively illuminate process constituents at a location spaced inwardly from the nozzle port.
It is a further object of the present invention to provide an illumination module having means for enabling periodic cleaning of a viewing window adjacent to the illumination module while the process vessel is operational.
It is a further object of the present invention to provide an illumination module having means for enabling periodic cleaning of a radiation exit end of an insertable radiation guide of the module for maintaining a high level of illumination.
It is a further object of the present invention to provide for non-axial illumination of a process for viewing through a separate viewing device.
In furtherance of these and other objects, an illumination module formed in accordance with a preferred embodiment of the present invention generally comprises a ring-shaped mounting member having an axially extending viewing passage therethrough, and an L-shaped radiation guide having a radiation entry end for communication with an external radiation source and a radiation exit end provided with a fused glass window for insertion within a vessel or pipeline containing process constituents. The radiation guide is arranged such that it extends through a radial guide hole in the mounting member and bends to run axially along the passage of the mounting member in close proximity to the wall of the passage so as to leave a majority of the cross-sectional area of the passage unblocked for viewing therethrough.
The illumination module can be clamped between a sight glass or camera viewing unit and the flange of a nozzle port, or between segments of a pipeline near a viewing window of the pipeline, to form an illumination and viewing assembly.
In a preferred embodiment, the mounting member includes a coarse flow duct system for enabling delivery of cleaning fluid to a sight glass or camera unit mounted adjacent thereto, and the mounting member shares a fine flow duct system with an outer housing of the radiation guide for enabling delivery of cleaning fluid to the fused glass window at the radiation exit end of the guide.
The illumination module of the present invention, and the preferred features thereof, can be used separately or in any combination with other modular accessories beyond a sight glass or camera viewing unit.